I described what I wanted to achieve in my original posting. To recap, I want to have a page with several delete buttons. Clicking on one button would produce parameter
delete_23.x=56
to be sent => we parse that, and delete item with ID 23 from database. Choosing a different delete -button would send parameter
delete_304.x=144
=> we delete item with ID 304.
I am aware that I can use the approach you suggested (parse request parameters manually), and have been doing that for ages before I started learning Struts :) I was just expecting that Struts would somehow help me with this task. I have been looking into indexed properties but I have not quite figured out how to properly implement this kind of functionality using them.
I finally figured out a reasonably satisfying way to do this while using Struts to help as much as possible:
public class ChoicesForm extends ActionForm { private Collection choices;
private ImageButtonTracer deleteButton; public void reset(ActionMapping arg0, HttpServletRequest arg1) {
this.choices = new ArrayList();
this.deleteButton = new ImageButtonTracer();
} public ChoiceView getChoice(int index) {
// if struts tries to get item with id index,
// and it does not exist,
// add new items until ok.
while (choices.size() <= index) {
choices.add(new ChoiceView());
}
List lChoices = (List) choices;
return (ChoiceView) lChoices.get(index);
} public Collection getChoices() {
return choices;
}
public void setChoices(Collection collection) {
choices = collection;
}
public ImageButtonTracer getDeleteButton() {
return deleteButton;
}
public void setDeleteButton(ImageButtonTracer tracer) {
deleteButton = tracer;
}
}public class ImageButtonTracer {
private Map clickedButtons; public ImageButtonTracer() {
clickedButtons = new HashMap();
} public Button getItem(int index) {
Button toReturn = (Button) clickedButtons.get(new Integer(index));
if (toReturn == null) toReturn = new Button();
clickedButtons.put(new Integer(index), toReturn);
return toReturn;
} public void setItem(int index, Button button) {
logger.debug("setItem(" + index + ")");
clickedButtons.put(new Integer(index), button);
} public Collection getClickedButtonIndexes() {
return clickedButtons.keySet();
} public class Button {
private int x;
private int y; public int getX() { return x; }
public int getY() { return y; }
public void setX(int i) { x = i; }
public void setY(int i) { y = i; }
}
}public class ChoiceView implements Serializable {
private String key;
private String name;
private String description;... + getters & setters }
<html:form action="/SaveChoices" method="GET">
<table border=1>
<logic:iterate id="choice" name="choicesForm" property="choices">
<tr>
<td><bean:write name="choice" property="key"/><html:hidden indexed="true" name="choice" property="key"/></td>
<td><html:text indexed="true" name="choice" property="name"/></td>
<td><html:text indexed="true" name="choice" property="description"/></td>
<td><html:image indexed="true" src="delete.gif" property="deleteButton.item"/></td>
</tr>
</logic:iterate>
</table>
<br><html:submit/>
</html:form>
public class SaveChoicesAction extends Action {
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
ChoicesForm cform = (ChoicesForm) form; ChoiceDAO dao = new ChoiceDAO();
// UPDATE
Iterator i = cform.getChoices().iterator();
while (i.hasNext()) {
ChoiceView view = (ChoiceView) i.next();
Choice toUpdate = ChoiceView.createChoice(view);
dao.update(toUpdate);
} // DELETE
Collection deletedIds =
cform.getDeleteButton().getClickedButtonIndexes();
if (deletedIds != null) {
Iterator d = deletedIds.iterator();
while (d.hasNext()) {
int deleteIndex = ((Integer) d.next()).intValue();
ChoiceView toDelete = cform.getChoice(deleteIndex);
Choice choice = ChoiceView.createChoice(toDelete);
dao.delete(choice);
}
}
return mapping.findForward("success");
}
}ImageButtonTracer can be simplified a bit if one assumes that only one button can be clicked per request (as is the case) => public Collection getClickedButtonIndexes() can be changed to public int getClickedButtonIndex(). This works, and I can use indexed properties somewhat comfortably.
Any improvements / alternatives are welcome.
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